Create lightweight, unprivileged container image "Hello MicroShift"

Basically Containerfile producing small (smaller the better) image that would serve "Hello MicroShift" on http 8080, running as nonroot to use in our test suite.

In one of our tests we're using:

image: busybox:1.35
command: ["/bin/sh"]
args: ["-c", "while true; do echo -ne \"HTTP/1.0 200 OK\r\nContent-Length: 16\r\n\r\nHello MicroShift\" | nc -l -p 8080 ; done"] 

• We'll put Containerfile in microshift repository and setup quay to build that image on update and expose as quay.io/microshift/hello-microshift
• it would be good to have a proper httpd rather than hack from code ^